Jungle Conceals Ebola Origins

The search is underway to find the source of the virus responsible for the current outbreak of Ebola haemorrhagic fever in Gabon. As with previous epidemics there seems to be a link with primates. Searching for the cause of the first outbreak in Gabon in 1994, investigators were told of the deaths of many apes in the forest nearby but none were found. In the 1996 epidemic, 13 people became ill after butchering a dead chimpanzee.

The New York-based Wildlife Conservation Society (WCS) is working on-site with personnel from the Centre International de Recherches Medicales de Franceville (CIRMF) and Ecosystemes Forestiers d’Afrique Centrale (ECOFAC) to survey villagers about wildlife

mortality and contacts, and to confirm reports by locating the carcasses where possible.

According to William Karesh of the WCS there have been verbal reports from local people of gorillas, chimpanzees, duikers (small antelopes), and several other mammals being found dead at various forest sites near to the outbreak in Gabon. Two of the human cases resulted from people eating or coming into contact with dead gorilla.

The virus could be spread among primates and other animals that share common watering pools and eat the same vegetation; or even be spread by insects. Some scientists think that plants and insects could be natural reservoirs for the virus, although attempts to grow Ebola virus in them have proved unsuccessful.

It has also been suggested that emergence of Ebola virus is caused by human encroachment into forest areas, but Karesh points out that people have been living in the forests of Gabon for centuries, perhaps in larger numbers than today. The recent emergence of Ebola virus may merely reflect improved reporting and contact with the countries involved, and the virus may have been circulating for hundreds of years.

It is hoped that widening the investigation to include the spread of Ebola virus in wildlife, rather than restricting the focus to the human disease, could prove fruitful in unravelling some of the mystery surrounding its epidemiology.